Electronic lock

ABSTRACT

A key operated electronic lock is disclosed. A serial stream of bits representing coded information is generated when a coded key having a plurality of apertures is moved between a light source and a pair of phototransistors. The serial stream of bits is stored in a shift register, and decoded by means of a decoder circuit which operates a locking solenoid.

United States Patent 1191 1 3,845,362 Roe 1 Oct. 29, I974 1 ELECTRONICLOCK [76] Inventor: Bruce C. Roe, PO. Box 253, 'l' Drummer-J MlnerAurora "L 60540 AS81810!!! ExammerHarry E. Moose, Jr.

Attorney, Agent, or FirmPeter Vtsserman [22] Filed: Aug. 20, 1973 21Appl. No: 390,162

[58] Field of Search... 317/134; 340/149 A, 164 R, 340/63, 64; 307/10AT; 250/555, 556, 568, 569; 70/277, 278, DIG. 51

[57] ABSTRACT A key operated electronic lock is disclosed. A serialstream of bits representing coded information is generated when a codedkey having a plurality of apertures is moved between a light source anda pair of phototransistors. The serial stream of bits is stored in ashift register, and decoded by means of a decoder circuit which operatesa locking solenoid.

[56] References Cited UNITED STATES PATENTS 7 Claims, 4 Drawing Figures3,688,269 8/1972 Miller ..340/149A 101 104 1mm 5mm :102 M510 1 if SHIFTrmsrg/e Q0 I 131 m -m R 112 1/ .7 I A 114 a l m5 103 y f ag f, 116 E cI31 134 100 3 1 111 113 s R l a 141 our -SLOPE c 1 o l 132 I10 TRIGGER Ll 0- 1 1 132 15a 1 l T nrsrr 01mm 5 R- l D L l 1 l l 1 4 l l I i ll 6 cl s STAGER l 1 9 i l O L 1 PAIENIEII on! 29 m4 J u o m $25 w} u u o m aq r L n N o N 111 m} :35 M W N E5 7 2 5 E983 H 0 Q H was? we: I. r is$53 w E 3 ESQ 3 o o I m w @2 $2? q 3. m2 m3 r k 1 v: n m Q N L E E 2&3 aE t v, 5 2 =23 3% g 5 N2 ELECTRONIC LOCK BACKGROUND OF THE INVENTION l.Field of the Invention The invention relates to an electronic lock andmore particularly to an electronic lock operated in response to apredetermined code stored in a shift register and generated by sliding amultiaperatured coded key between a source of light energy and aphotosensitive device.

2. Prior Art Prior art electronic locks operable by means of a coded keyare known. In some prior art locks a coded key operates a plurality ofelectrical switches in parallel. Other prior art locks are known whichemploy a coded card read by mechanical means to activate a numberofswitches. In U.S. Pat. No. 3.749.930 an electronically operated switchis disclosed having a plurality of photocells. one for each possiblenotch ofa coded key. which are exposed to a light source when the keyhas been properly inserted in the key slot.

Such prior art locks all have the disadvantage that the key reading unitmust have as many switches as there are code positions on the coded keyor card. It is known to be desirable in electronic locks to use a keyhaving a large number of code positions in order to enhance the value ofthe lock. In the prior art arrangements. an increased number of codeshas resulted in an increase in the size of the switch and an increase inthe number of wires from the switch to the locking device;

SUMMARY OF THE INVENTION In accordance with the present invention. acoded key is read when the key is moved by sliding motion between asource of light energy and a pair of photosensitive devices. The key inaccordance with the invention has two sets of aligned apertures. and thephotosensitive devices are intermittently exposed to energy from thesource generating a serial stream of pulses when the key is insertedinto the key slot. The pulses generated by one of the photosensitivedevices are applied to the input terminals of a shift register. whilethe pulses generated by the other photosensitive device are employed toadvance the shift register. In this manner a serial stream of pulsesgenerated by the insertion of the key into the key slot is stored in amultistage shift register. A decoder circuit reads the contents of theregister in parallel and operates a locking solenoid when apredetermined code has been stored in the shift register. In accordancewith the present invention. a coded key may have any number ofcodedpositions. but only two photosensitive devices will be required at thekey reading position and only two conductors are required from the keyreading position to the shift register and decoder circuit. which may belocated immediately adjacent the locking solenoid. In an automobile thelocking solenoid may be located at the starter motor and the decodingcircuit may be made an integral part of the starter assembly.

In one illustrative embodiment of the invention. the coded key has aplurality of evenly spaced rectangular openings aligned longitudinallyapproximately along the center line axis of the key. and a plurality ofslots are cut in one edge of the key. The openings along the axis of thekey are employed to generate shift register advance pulses. The slots inthe edge of the key contain the code and are used to generate coded datapulses which are gated into the shift register. the presence of a slotrepresenting a logical l, and the absence of a slot representing alogical The slots in the key are so arranged that the center of eachslot is substantially aligned with one edge of one of the rectangularopenings. Electronic circuitry is employed which detects the change fromabsence of a signal to presence of a signal and vice versa and each timea rectangular opening passes the light source. a photo-transistoraligned with the rectangular holes generates a single pulse and theelectronical circuit generates two shift pulses. If a slot is present inalignment with the edge of a rectangular hole. a data signal will begenerated by a phototransistor aligned with the edge of the key and willbe gated into the shift register by a shift pulse which also shifts thecontents of the first stage of the register to subsequent stages. Inthis manner a logical I is gated into the shift register for each slotpresent in the edge of the key and a logical 0" is gated into the shiftregister for each code position of the key in which no slot exists.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a schematic of an electricalcircuit of an il lustrative embodiment of the invention.

FIG. 2 shows an illustrative coded key and a sectional view of areceptacle into which the coded key may be inserted.

FIG. 3 shows an enlargement of a portion of the illustrative key.

FIG. 4 is a timing diagram showing approximate wave forms of signalsoccurring at indicated points of the circuit of FIG. I.

DETAILED DESCRIPTION FIG. 1 is a circuit schematic of the electricalcircuit of the illustrative embodiment. When a coded key such as key 200shown in FIG. 2 is inserted in the key receptacle I00 the flow of lightenergy from the light source I01 to the light sensitivephoto-transistors I02 and I03 is blocked intermittently causing thephoto-transistors to generate pulsed output signals. The openings I04 ofthe key receptacle provide a path for the passage of light from thesource to the photo-transistor I02 and are aligned just below the upperedge of the key 200 when the key is positioned in the receptacle. Apositive signal is generated on the data signal line I06 when one of theslots 201 is in alignment with the holes I04, while no signal isproduced on the line I06 when the flow of light energy tophoto-transistor I02 is blocked by any portion of the key. The signalline I06 is connected to one input terminal of the first stage of theshift register "0 and to an inverter gate 107. The output signal lineI08 of inverter gate I07 is connected to another input terminal of thefirst gage of shift register I10.

When the key is positioned in the receptacle the line along whichapertures are aligned will be in alignment with the holes I05. Apositive signal is generated on the clock signal line 110 when one ofthe apertures 202 is in alignment with holes and no signal is generatedon the clock signal line when the flow of light energy tophoto-transistor 103 is blocked by any portion of the key 200. Thetransition from absence of a signal to presence of a signal on the clocksignal line 110 is relatively slow since the key 200 is moved into thekey receptacle manually which is necessarily slow in comparison with thereaction time of the electronic circuitry. In order to avoid thegeneration of extraneous clock pulses during transition. an operationalamplifier II] is employed with a feedback resistor 2 having a value R2which may be chosen to be twice as great as the value R] of the inputresistor 113. Choosing the values of the two resistors in this mannerthe operational amplifier I l I will have an effective hysteresischaracteristic, which under most circumstances will as sure a singlepulse at the output of the operational amplifier lll as a slowly varyingsignal occurs on the clock signal line ll0. Operational amplifiersconnected into a circuit in the manner shown in FIG. I are well known inthe art and need no further elaboration.

The circuit of FIG. I incorporates a positive slope trigger H4 and anegative slope trigger H5. The positive slope trigger ll4 generates arelatively short duration positive output pulse in response to a changeat its input terminal from an existing voltage level to a higher voltagelevel. The negative slope trigger 115 generates a relatively shortduration positive output pulse when the signal at its input changes froman existing voltage level to a lower voltage level. The output pulse ofthe trigger circuits may be adjusted to have a duration of approximatelyI milli second. Trigger circuits such as circuits I14 and US are wellknown in the art and no specific description of these circuits isrequired. The output terminals of the slope trigger circuits 4 and IISare connected to an OR gate 116 which generates an output signal when asignal is applied to either of its input terminals. The output terminalof the OR gate is connected to the shift input connection of the shiftregister I20. which receives a shift pulse each time a transition occurson clock signal line 110.

The timing diagram of FIG. 4 shows approximate wave forms of signalsoccurring at indicated points of the circuit of FIG. I. The wave form Aof FIG. 4 corresponds to the output of the operational amplifier l1] andis generated when the apertures 202 of key 200 are moved past the holesI thereby interrupting the flow of light energy from the source I01 tothe phototransistor 103. The leading edge 40] of the wave form occurringat point A in the circuit is generated when the forward edge of one ofthe apertures. for example the edge is moved in front of holes 105 ofthekey receptacle I00. The trailing edge 402 of the wave form occurring atpoint A will be generated when the rearward edge of one of the aperturessuch as edge 302 is moved past the holes I05 in the key receptacle 100.As indicated above. the positive slope trigger ll4 generates arelatively short duration pulse when a transition at its input terminaloccurs front an established voltage level to a relatively higher voltagelevel as. for example. the transition of leading edge The wave formwhich occurs at the output terminal of the positive slope trigger IN isidentified by the letter Bin FIG. 4. Similarly. the negative slopetrigger ll5 generates an output pulse when the signal at its inputterminal makes a transition to a relatively lower voltage level. such asthe transition of trailing edge 402. The wave form occurring at theoutput of the negative slope trigger I15 is identified by the letter Cin FIG. 4. The OR gate 116 generates an output signal whenever a signaloccurs on either of its input terminal. which is used to shift data intothe shift register and to advance the data from the first stage of theshift register to subsequent stages.

Thus. as can be seen a shift pulse is generated first when the forwardedge of one of the apertures 202 of key 200 is moved past the holes I05and another shift pulse is generated when the rearward edge of theaperture is moved past the holes 105. The coded key shown in FIG. 2 has5 apertures. indicating that a total of 10 shift pulses will begenerated as the key is inserted in the key receptacle I00.

As can be seen from the enlarged view of the coded key in FIG. 3, theforward and rearward edge of each aperture 202 is aligned with theapproximate center of one of the slots 20! which have been cut in theupper edge of the key. For illustrative purposes the forwardmost 3apertures of the key have been labeled .r. y. and z and the three pulsesx. y, and z in FIG. 4 represent the wave form at point A which isgenerated when the key 200 is inserted in the key receptacle and thecorrespondingly labeled apertures are moved past holes 105. Furthermore.the first six places where slots might be cut in the upper edge of thekey are indicated by the letters m. n. o, p. q. and r. In the key ofthis illustrative example slots have been cut in spaces n. p. and q ofthe first six spaces of the key. The wave form identified by the letterI in FIG. 4 shows that the pulses n. p. and q will occur when the codedkey 200 is inserted in the key receptacle I00 and the correspondinglylabeled slots are moved past holes 104. For a different codedconfiguration, pulses m, u. and r could occur.

As can be seen from FIG. 4, a shift pulse is generated at the point S inthe circuit in coincidence with each possible pulse at point I in thecircuit. The shift register I20 may be any well-known shift register inwhich data is advanced by means ofa series of shift pulses. The signaloccurring at the point I and the inverse thereof are applied to theinput terminals of the first stage of the shift register. It will beunderstood that the equivalent of a logical 1" will be gated into thefirst stage of the shift register if a positive signal is present at thepoint I when the shift pulse occurs and that the equivalent of logical"0 will be gated into the first stage of the shift register ifthere isno positive signal at point I when the shift pulse occurs.

The shift register I20 comprises a plurality of shift register stages.As mentioned. the illustrative key 200 has five apertures 202 and canhave as many as ten code slots 20] cut along the upper edge of the key.A shift register stage is provided for each possible slot. Each shiftregister stage has a pair of input terminals. a shift terminal. a pairof output terminals and a reset terminal. The input terminals of thefirst stage. stage 0 ofthe shift register [20. are connected to thelines I06 and I08. The signal occurring on line 108 is the inverse ofthesignal occurring on the data signal line I06, having been inverted bymeans of the inverter 107. The input terminals of stage 1 through stage9 of the shift register I20 are connected to the output terminals of thepreceding register stage. One of the output terminals of each of theshift register stages is connected to a decoder circuit I30 whichcomprises a plurality of inverters l3l. The input terminals of the codercircuit may be connected directly to an output AND gate I34 or may beinverted through an appropriate inverter circuit 13]. by the selectiveconnection of the jumper wires 132.

The code cut into the illustrative key 200 by means of the slots 20]comprises a l0-bit code and as can be seen the code can be representedin terms of ls and Os as follows:

As will be understood with reference to the drawing. when theabove-noted code is inserted in the shift register 120, the first andlast stages of the shift register will contain a 0" and the second stageof the shift register will contain a I." Since the output signal fromthe first and last stages of the shift register are inverted by invertergates 13], and the output signal from the second stage of the shiftregister is not inverted. the corresponding input terminals of the ANDgate 134 will be presented with a signal equivalent to a logical 1."Similarly, by selectively connecting the jumper wires 132 in the decodercircuit 130 all input terminals of AND gate 134 will be presented with alogical 1" if the above-noted code is inserted in the shift registerI20. Clearly any other -bit code can be devised which through properconnection of the jumper wires will cause all input terminals of the ANDgate 134 to be presented with a logical The coil of a locking solenoid141 is energized by means of a signal generated by AND gate 134 when apredetermined code. appears in the shift register 120. The lockingsolenoid may. of course; be used to perform any number of functions,such as allowing the en gagement of a starter in an automobile or theflow of current to the ignition circuit. or to perform numerous otherlocking functions.

When the key is removed from the key receptacle 100 the shift registeris reset by a pulse applied to reset terminal R of each of the stages ofthe shift register. The reset pulse is generated by means of the resetcircuit [50 which generates a short duration output pulse when thephoto-transistor 103 is continually exposed to the light source 101 forgreater than a predetermined period oftime which substantially exceedsthe duration of the pulses A. shown in FIG. 4; generated by theinsertion ofthe key into receptacle 100. The reset circuit 150 maycomprise a capacitor timing circuit having a relatively long timeconstant and a one-shot multivibrator to generate a single reset pulseafter the key has been removed from the receptacle.

lt will be understood that the above is the description of anillustrative embodiment of applicants invention and it is recognizedthat numerous other arrangements may be devised by those skilled in theart without departing from the basic principles of the invention.

What is claimed is:

1. An electronic locking arrangement comprising:

a source of light energy;

a first and a second sensor responsive to intermittent exposure to lightenergy from said source to generate a plurality of multi-state signals;

a coded key having a first and a second set of aligned apertures;

a key guide for guiding said key in a path between said source and saidsensors wherein said first set of apertures are aligned along a lineintersecting a line extending from said source to said first sensor andsaid second set of apertures are aligned along a line intersecting aline extending from said source to said second sensor. whereby saidsensors are intermittently exposed to light energy from said source whensaid key is slidingly inserted into said guide;

said apertures of said first set each having a substan tiallyrectangular shape and having a forward edge and a rearward edge. thecenter of each of said ap ertures of said second set being approximatelyaligned with one of said forward or one of said rearward edges;

a multi-state shift register;

means for connecting said sensors to said shift register. said shiftregister being responsive to signals from said first sensor to store thestates of signals generated by said second sensor in said shiftregister; and

means connected to said shift register for selectively operating alocking solenoid.

2. An electronic locking arrangement in accordance with claim 1, whereinsaid means for connecting said first sensor to said shift registercomprises first pulse generating means responsive to the transition froma first state to a second state of a signal from said first sensor togenerate a first output pulse and second pulse generating meansresponsive to the transition from said second to said first state of asignal from said first sensor to generate a second output pulse andmeans responsive to said first and second output pulses to generate ashift register advance pulses.

3. An electronic locking arrangement in accordance with claim 2, andfurther comprising a signal amplification circuit having signal feedbackconnected between said first sensor and said first and said second pulsegenerating means. and having an effective hysteresis characteristic.

4. An electronic locking arrangement in accordance with claim 1, andfurther comprising reset means responsive to a signal from said firstsensor of substantially longer duration than signals produced by normalinsertion of said key in said guide to generate a reset signal forresetting said shift register.

5. In combination,

a key and an electronic lock having a source of light energy, a pair oflight sensitive detectors for generating an output signal when exposedto light energy emitted by said source. and means responsive to signalsfrom said detectors to generate a lock operative signal;

said key having at least one longitudinally extending edge. and aplurality of code slot areas along said edge defining slots which may becut across said edge and having predetermined spacing between centers ofsaid areas;

a number of substantially rectangular holes in said key aligned along aline parallel to said edge. each of said holes having a first and asecond edge extending in a direction transverse to said line; and

the centers of each of said slots being in alignment with the first orthe second edge of one of said holes.

6. An electronic key lock comprising:

an energy emitting source;

a first and a second sensing device;

a coded key having a plurality of code apertures aligned along a firstline and a plurality of clock apertures aligned along a second line;

a key guide mounted between said source and said devices;

said first line of said key being aligned with said first device andsaid second line of said key being 7 aligned with said second device.when said key is in said guide;

said first device being responsive to intermittent exposure to saidsource resulting from sliding motion of said key in said guide togenerate a plurality of code pulses corresponding to the code aperturesof said key;

said second device being responsive to intermittent exposure to saidsource resulting from the sliding motion of said key in said guide togenerate a plurality of clock pulses corresponding to said clockapertures;

a pulse circuit comprising a signal amplification circuit having aneffective hysteresis characteristic, connected to said second sensingdevice and responsive to said clock pulses to generate shift registeradvance pulses;

shift register means having a plurality of stages, connected to saidfirst sensing device and said pulse circuit and responsive to saidadvance pulses to store said code pulses therein; and

means connected to said shift register and responsive to a predeterminedcode stored therein to generate a lock operate signal.

7. An electronic key lock comprising:

an energy emitting source;

a first and a second sensing device;

a coded key having a plurality of code apertures aligned along a firstline and a plurality of clock apertures aligned along a second line;

a key guide mounted between said source and said devices;

said first line of said key being aligned with said first device. andsaid second line of said key being aligned with said second device, whensaid key is in said guide;

said first device being responsive to intermittent exposure to saidsource resulting from sliding motion of said key in said guide togenerate a pluraltiy of code pulses corresponding to the code aperturesof said key;

said second device being responsive to intermittent exposure to saidsource resulting from the sliding motion of said key in said guide togenerate a plurality of clock pulses corresponding to said clockapertures;

shift register means having a plurality of stages. said shift registerbeing connected to said first and said second sensing devices andresponsive to said clock pulses to store said code pulses therein;

shift register reset means comprising a timing circuit and responsive toa signal from said second sensing device of substantially greaterduration than signals produced by normal insertion of said key in saidguide to generate a reset signal for resetting said shift registermeans; and

means connected to said shift register means and responsive to apredetermined code stored therein to generate a lock operate signal. l=t

1. An electronic locking arrangement comprising: a source of lightenergy; a first and a second sensor responsive to intermittent exposureto light energy from said source to generate a plurality of multi-statesignals; a coded key having a first and a second set of alignedapertures; a key guide for guiding said key in a path between saidsource and said sensors wherein said first set of apertures are alignedalong a line intersecting a line extending from said source to saidfirst sensor and said second set of apertures are aligned along a lineintersecting a line extending from said source to said second sensor,whereby said sensors are intermittently exposed to light energy fromsaid source when said key is slidingly inserted into said guide; saidapertures of said first set each having a substantially rectangularshape and having a forward edge and a rearward edge, the center of eachof said apertures of said second set being approximately aligned withone of said forward or one of said rearward edges; a multi-state shiftregister; means for connecting said sensors to said shift register, saidshift register being responsive to signals from said first sensor tostore the states of signals generated by said second sensor in saidshift register; and means connected to said shift register forselectively operating a locking solenoid.
 2. An electronic lockingarrangement in accordance with claim 1, wherein said means forconnecting said first sensor to said shift register comprises firstpulse generating means responsive to the transition from a first stateto a second state of a signal from said first sensor to generate a firstoutput pulse and second pulse generating means responsive to thetransition from said second to said first state of a signal from saidfirst sensor to generate a second output pulse and means responsive tosaid first and second output pulses to generate a shift register advancepulses.
 3. An electronic locking arrangement in accordance with claim 2,and further comprising a signal amplification circuit having signalfeedback connected between said first sensor and said first and saidsecond pulse generating means, and having an effective hysteresischaracteristic.
 4. An electronic locking arrangement in accordance withclaim 1, and further comprising reset means responsive to a signal fromsaid first sensor of substantially longer duration than signals producedby normal insertion of said key in said guide to generate a reset signalfor resetting said shift register.
 5. In combination, a key and anelectronic lock having a source of light energy, a pair of liGhtsensitive detectors for generating an output signal when exposed tolight energy emitted by said source, and means responsive to signalsfrom said detectors to generate a lock operative signal; said key havingat least one longitudinally extending edge, and a plurality of code slotareas along said edge defining slots which may be cut across said edge,and having predetermined spacing between centers of said areas; a numberof substantially rectangular holes in said key aligned along a lineparallel to said edge, each of said holes having a first and a secondedge extending in a direction transverse to said line; and the centersof each of said slots being in alignment with the first or the secondedge of one of said holes.
 6. An electronic key lock comprising: anenergy emitting source; a first and a second sensing device; a coded keyhaving a plurality of code apertures aligned along a first line and aplurality of clock apertures aligned along a second line; a key guidemounted between said source and said devices; said first line of saidkey being aligned with said first device, and said second line of saidkey being aligned with said second device, when said key is in saidguide; said first device being responsive to intermittent exposure tosaid source resulting from sliding motion of said key in said guide togenerate a plurality of code pulses corresponding to the code aperturesof said key; said second device being responsive to intermittentexposure to said source resulting from the sliding motion of said key insaid guide to generate a plurality of clock pulses corresponding to saidclock apertures; a pulse circuit comprising a signal amplificationcircuit having an effective hysteresis characteristic, connected to saidsecond sensing device and responsive to said clock pulses to generateshift register advance pulses; shift register means having a pluralityof stages, connected to said first sensing device and said pulse circuitand responsive to said advance pulses to store said code pulses therein;and means connected to said shift register and responsive to apredetermined code stored therein to generate a lock operate signal. 7.An electronic key lock comprising: an energy emitting source; a firstand a second sensing device; a coded key having a plurality of codeapertures aligned along a first line and a plurality of clock aperturesaligned along a second line; a key guide mounted between said source andsaid devices; said first line of said key being aligned with said firstdevice, and said second line of said key being aligned with said seconddevice, when said key is in said guide; said first device beingresponsive to intermittent exposure to said source resulting fromsliding motion of said key in said guide to generate a pluraltiy of codepulses corresponding to the code apertures of said key; said seconddevice being responsive to intermittent exposure to said sourceresulting from the sliding motion of said key in said guide to generatea plurality of clock pulses corresponding to said clock apertures; shiftregister means having a plurality of stages, said shift register beingconnected to said first and said second sensing devices and responsiveto said clock pulses to store said code pulses therein; shift registerreset means comprising a timing circuit and responsive to a signal fromsaid second sensing device of substantially greater duration thansignals produced by normal insertion of said key in said guide togenerate a reset signal for resetting said shift register means; andmeans connected to said shift register means and responsive to apredetermined code stored therein to generate a lock operate signal.